// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_ACTIVE_BLOB_REGISTRY_H_
#define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_ACTIVE_BLOB_REGISTRY_H_

#include <stdint.h>

#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "content/common/content_export.h"
#include "storage/browser/blob/shareable_file_reference.h"
#include <map>
#include <set>
#include <utility>

namespace content {

class IndexedDBBackingStore;

class CONTENT_EXPORT IndexedDBActiveBlobRegistry {
public:
    explicit IndexedDBActiveBlobRegistry(IndexedDBBackingStore* backing_store);
    ~IndexedDBActiveBlobRegistry();

    // Most methods of this class, and the closure returned by
    // GetAddBlobRefCallback, should only be called on the backing_store's task
    // runner.  The exception is the closure returned by GetFinalReleaseCallback,
    // which just calls ReleaseBlobRefThreadSafe.

    // Use DatabaseMetaDataKey::AllBlobsKey for "the whole database".
    bool MarkDeletedCheckIfUsed(int64_t database_id, int64_t blob_key);

    storage::ShareableFileReference::FinalReleaseCallback GetFinalReleaseCallback(
        int64_t database_id,
        int64_t blob_key);
    // This closure holds a raw pointer to the IndexedDBActiveBlobRegistry,
    // and may not be called after it is deleted.
    base::Closure GetAddBlobRefCallback(int64_t database_id, int64_t blob_key);
    // Call this to force the registry to drop its use counts, permitting the
    // factory to drop any blob-related refcount for the backing store.
    // This will also turn any outstanding callbacks into no-ops.
    void ForceShutdown();

private:
    // Maps blob_key -> IsDeleted; if the record's absent, it's not in active use
    // and we don't care if it's deleted.
    typedef std::map<int64_t, bool> SingleDBMap;

    void AddBlobRef(int64_t database_id, int64_t blob_key);
    void ReleaseBlobRef(int64_t database_id, int64_t blob_key);
    static void ReleaseBlobRefThreadSafe(
        scoped_refptr<base::TaskRunner> task_runner,
        base::WeakPtr<IndexedDBActiveBlobRegistry> weak_ptr,
        int64_t database_id,
        int64_t blob_key,
        const base::FilePath& unused);

    std::map<int64_t, SingleDBMap> use_tracker_;
    std::set<int64_t> deleted_dbs_;
    // As long as we've got blobs registered in use_tracker_,
    // backing_store_->factory() will keep backing_store_ alive for us.  And
    // backing_store_ owns us, so we'll stay alive as long as we're needed.
    IndexedDBBackingStore* backing_store_;
    base::WeakPtrFactory<IndexedDBActiveBlobRegistry> weak_factory_;

    DISALLOW_COPY_AND_ASSIGN(IndexedDBActiveBlobRegistry);
};

} // namespace content

#endif // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_ACTIVE_BLOB_REGISTRY_H_
